Thyroid Stimulating Hormone (TSH) and thyroxine (T4). Generally, a TSH reading above normal means a person has hypothyroidism. A T4 test measures the actual amount of thyroid hormone circulating in the blood. In hypothyroidism, the level of T4 in the blood is lower than normal. Blood drawn from people with Hashimoto's thyroiditis typically reveals an increase in the number of antibodies against thyroid-specific proteins, including thyroperoxidase and
thyroglobulin.